all: invert use_golang_protobuf_v1 tag

Invert the build tag such that the default is to use the reimplementation
that uses v2 under the hood.

Change-Id: I04ee912ddd59b387c2fbf0146b779dd99b060e93
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/169297
Reviewed-by: Herbie Ong <herbie@google.com>

proto/hooks_disabled.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !proto_reimpl
+// +build use_golang_protobuf_v1
 
 package proto
 

proto/hooks_enabled.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build proto_reimpl
+// +build !use_golang_protobuf_v1
 
 package proto
 

proto/properties.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !proto_reimpl
+// +build use_golang_protobuf_v1
 
 package proto
 

proto/properties_alt.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build proto_reimpl
+// +build !use_golang_protobuf_v1
 
 package proto
 

test.bash

@@ -11,7 +11,7 @@ FAIL="\x1b[31mFAIL"
 RESET="\x1b[0m"
 
 echo -e "${BOLD}go test${RESET}"
-RET_TEST=$((go test ./... && go test -tags proto_reimpl ./...) | egrep -v "^(ok|[?])\s+")
+RET_TEST=$((go test ./... && go test -tags use_golang_protobuf_v1 ./...) | egrep -v "^(ok|[?])\s+")
 if [[ ! -z "$RET_TEST" ]]; then echo "$RET_TEST"; echo; fi
 
 echo -e "${BOLD}go generate${RESET}"